disk write error?????

help having PC trouble. Screen gets blue and says Disk write error unable to write to disk in drive c data or files may be lost. I run scan disk and it stops won't finish. i run defrag and it says I need to run scan disk to fix a problem. it is a never ending circle. if i take windows off then redo it will it fix this?? took me a good bit to get on here tonight hopefully i can get back to see an answer? when I check my mail it happens to if I keep pressing spacebar it will go away for a bit. this happened after I added Norton system works disk,. I took it back off and it is still doing it. any advice appreciated